An easy recipe for homemade Swiss Meringue Buttercream.
- 290 grams (1 and 1/4 cups or 2.5 sticks) unsalted butter, cut in 1/2 inch cubes
- 6 egg whites
- 250 grams (1 and 1/4 cups) caster sugar or granulated sugar
- 2 teaspoons vanilla extract
- Pinch of salt
- Before you begin: Chose a medium saucepan and a medium heatproof bowl that you can use for your double boiler. You’ll want to use a bowl that will neatly fit on top of your saucepan, but the bottom of the bowl CANNOT be touching the water below. (See photo below). Wipe down your bowl, making sure it’s completely dry and there’s no grease, residue, or crumbs left in it. Remove butter from the fridge and set aside. Carefully separate your egg whites.
- Add egg whites and sugar in your mixing bowl and whisk by hand to combine. Place bowl on top of a saucepan that’s filled with a few inches of water and turn on medium heat.
- Continue to whisk by hand until your sugar has completely dissolved and your egg mixture has reached 70 C / 160 F. You can check this using a candy thermometer. The eggs will be thick and frothy. Remove from heat.
- Place eggs in the bowl of a stand mixer fitted with a whisk attachment. Whisk on medium speed until egg whites become thick and voluminous and reach stiff peaks. This can take around 10 minutes. The egg whites should hold their shape and not droop. The mixture should also be completely cooled.
- Turn your mixer down to low speed, then slowly add your butter, piece by piece. As you add your butter, your meringue mixture may turn soupy, and/or eventually look curdled – this is ok.
- Continue until you’ve added all your butter. Turn your mixer up to medium speed and continue to whisk until frosting comes together and is smooth again. Do not worry about over-mixing – keep going.
- Finally, add vanilla and salt. Mix briefly. Then remove bowl from mixer and use a spatula to give it one final stir by hand, getting rid of any air bubbles.
Butter: Your butter needs to be cool, but not fridge cold. I recommend getting it out of the fridge when you are ready to start, so it has time to cool slightly.
Soupy frosting: If your meringue wasn’t completely cooled or your butter was too warm, your meringue may appear thin and soupy after you add the butter. Don’t worry if this happens, you can pop it in the fridge, wait 20 minutes and then whisk again.
Curdled frosting: Once you add the butter, your frosting may appear curdled. This is normal. Keep whisking and it will come back together and be smooth and creamy again. For more troubleshooting tips, check out this article by Serious Eats.
Make ahead: You can make this frosting ahead of time and keep it in the fridge. The butter will solidify making it firm. To use, let it come back to room temperature, then whisk it again until smooth and creamy. You can also freeze it. In the same way, you’ll need to let it thaw before whisking again.